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© Blue Graphics Concept Sauer-Danfoss Design Closed Circuit Introduction, May 2012.

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Presentation on theme: "© Blue Graphics Concept Sauer-Danfoss Design Closed Circuit Introduction, May 2012."— Presentation transcript:

1 © Blue Graphics Concept Sauer-Danfoss Design Closed Circuit Introduction, May 2012

2 2 MENU Main Menu Basic Hydrostatic (closed circuit) System Overview Functionality of components Hydraulic Fluids FiltrationReservoir Heat Exchanger

3 3 MENU Main Menu Basic Hydrostatic (closed circuit) System Overview Functionality of components Hydraulic Fluids FiltrationReservoir Heat Exchanger

4 4 MENU 1. System Overview Hydrostatic Transmission Continuously variable speed w/o loss of traction A B Speed [km/h] T r a c t i v e F o r c e [ N ] Pump Ratio Motor Ratio Installed Engine Power hydrostatic transmission - source 1 -

5 5 MENU 1. System Overview Hydrostatic Transmission Motor output torque and speed depends on pump and motor displacement Speed of hydrostatic transmission is reciprocal to displacements Torque is proportional to displacements

6 6 MENU Main Menu Basic Hydrostatic (closed circuit) System Overview Functionality of components Hydraulic Fluids FiltrationReservoir Heat Exchanger

7 7 MENU 2. Functionality of Components Integrated Charge Pump

8 8 MENU 2. Functionality of Components Integrated Charge Pump Charge pump is a fixed displacement pump (gerotor-type) which is directly connected to the pump input shaft Charge pump displacement should be sized to approximately 10% of whole system displacement (pump and motor(s) displacements) in most applications

9 9 MENU 2. Functionality of Components Charge Pump - Functions Charge Pump flow rate functions: Replenish leakage oil of pump and motor Replenish loop flushing oil through the flushing valve Provide flow for the servo control systems Provide flow for auxiliary circuit functions e.g. parking brake release Charge Pump pressure functions: Maintain low loop pressure Provide sufficient pressure to activate the servo control systems

10 10 MENU 2. Functionality of Components Charge Pressure Relief Valve

11 11 MENU 2. Functionality of Components Charge Pressure Relief Valve Charge pressure relief valve is necessary to maintain low loop pressure Protects the charge pump by limiting the charge pressure Excess charge pump output flow is directed into the pump case

12 12 MENU 2. Functionality of Components Charge Check Valve

13 13 MENU 2. Functionality of Components Charge Check Valve It protects the charge pressure system (charge pump), otherwise a backflow from high pressure side will damaged the charge pump

14 14 MENU 2. Functionality of Components Loop Flushing System

15 15 MENU 2. Functionality of Components Loop Flushing System Loop Flushing is necessary because of cooling requirements and contamination removal of system circuit The LF-system removes fluid from the low pressure side of the closed circuit system Loop Flushing valves are available with different flow rates to optimize flush flow requirements in all system operating conditions

16 16 MENU 2. Functionality of Components High Pressure Relief Valve (HPRV)

17 17 MENU 2. Functionality of Components High Pressure Relief Valve (HPRV) High pressure relief valves are needed in hydrostatic transmission systems to limit maximum pressures –Pressures above the product ratings will damage the transmission –HPRV protect pumps, motors, hoses and other system components

18 18 MENU 2. Functionality of Components Pressure Limiter Pressure Limiter is a non dissipative high pressure control Limits the heat generated in the system when pressures are too high PL changes the displacement of the pump in response to high system pressure

19 19 MENU 2. Functionality of Components Bypass Bypass function allows an internal connection to be made between the two loops in the hydrostatic transmission Function allows the vehicle to be moved without the engine running –Allows for disabled vehicles to be loaded onto a trailer or moved off the road –Intended to be for slow, short durations otherwise the hydrostatic transmission can be damaged

20 20 MENU Main Menu Basic Hydrostatic (closed circuit) System Overview Functionality of components Hydraulic Fluids FiltrationReservoir Heat Exchanger

21 21 MENU 3. Hydraulic Fluids What do you know about Hydraulic Fluids?

22 22 MENU 3. Hydraulic Fluids Overview Hydraulic Fluid Groups 1.Mineral oil based hydraulic fluids 2.Biogradeable hydraulic fluids Syntetic ester (HEES) Rape oil alkaline (HETG) 3.Fire resistance fluids ATEX Regulation

23 23 MENU 3. Hydraulic Fluids Recommended Hydraulic Fluids Find recommended Hydraulic Fluids for Sauer-Danfoss hydrostatic components in Technical Literature* Fluids meeting the technical literature requirements will very likely provide acceptable unit life field testing is the only truly indication of fluid performance Sauer-Danfoss warranty claim policies do not apply for fluid related damage *: Hydraulic Fluids and Lubricants Technical Information; page 20

24 24 MENU 3. Hydraulic Fluids Physical Behavior 1.Viscosity Viscosity grade (VG) Depends on temperature and pressure Compromise between flow losses and leakage 2.Density Depends on temperature and pressure

25 25 MENU 3. Hydraulic Fluids Physical Behavior Temperature-BehaviorPressure-Behaviour Temperature kinematic Viscosity

26 26 MENU 3. Hydraulic Fluids Viskosity and Temerature Limits Viscosity and temperature limits in the table Viscosity and temperature limits in technical information* are to be observed Under normal operating condition it is recommended to keep the temperature in the range of 30 °C to 60 °C Rule of thumb: fluid temperature increase from 80 °C [176 °F] to 90 °C [194 °F] may reduce fluid life by 50 % *: Hydraulic Fluids and Lubricants Technical Information; page 19

27 27 MENU 3. Hydraulic Fluids Additives Improvement of oil attributes Viscosity-temperature behavior Wear protection Corrosion protection Ageing resistance Foam prevention Bond to dirt particles

28 28 MENU 3. Hydraulic Fluids Selection Criteria Manufacturers instructions Release of diverse oils Depends on system Application (vehicle, temperature conditions) Fill rate Application environment Climate Area of application (i.e. environmental, flammability regulations, etc.)

29 29 MENU 3. Hydraulic Fluids Additional Information Technical Information Hydraulic Fluids and Lubricants (520L0463) Technical Information Experience with Biodegradable Hydraulic Fluids (520L0465)

30 30 MENU Main Menu Basic Hydrostatic (closed circuit) System Overview Functionality of components Hydraulic Fluids FiltrationReservoir Heat Exchanger

31 31 MENU 4. Filtration Contamination Sources of contamination: –Installation –System components –Fill oil –Repair of a unit Types of contamination: –Metal –Synthetic materials –Organic materials –Plastic –Water –Etc. Scratches on Piston Shoe

32 32 MENU 4. Filtration Cleanliness Classes ISO : Specification of three cleanliness classes correlated to particle size 4; 6; 14 [μm] Example: ISO 18/16/13 number of particles 1/ml cleanliness classes (ISO 4406) 0,01-0,021 0,02-0,042 0,04-0,083 0,08-0,164 0,16-0,325 0,32-0,646 etc

33 33 MENU 4. Filtration Cleanliness Classes Sauer-Danfoss recommends the cleanliness classes below for different applications* Product Required cleenliness class ISO Steering components with open center22/20/17 Orbital motors22/20/16 Steering components with LS and closed center 21/19/16 Proportional spool valves Axial + radial piston pumps and motors 22/18/13 Gear pumps and motors Cartridge and electrohydraulic valves18/16/13 Maximum class at machine start up 25/22/17 *: Design Guideline for Hydraulic Fluid Cleanliness Technical Information (520L0467), p. 13, Spreadsheet: Fluid cleanliness requirements according to product

34 34 MENU 4. Filtration Kind of Filtration Partial flow filtration +Small filter - Partial backflow of oil w/o filtration - Charge pump unprotected (pre-filtration necessary)

35 35 MENU 4. Filtration Kind of Filtration Full flow filtration +Complete oil filtration +Small filter - Charge pump unprotected ( pre-filtration necessary)

36 36 MENU 4. Filtration Kind of Filtration Suction filtration +Charge pump protected - Large filter surface necessary -Disadvantageous at low temperature

37 37 MENU Main Menu Basic Hydrostatic (closed circuit) System Overview Functionality of components Hydraulic Fluids FiltrationReservoir Heat Exchanger

38 38 MENU 5. Reservoir Overview Art der Filterung Tasks: Fluid reservoir Ensures there is enough oil for hydraulic system Cooling Separates dirt, water and air Assures smooth fluid flow (laminar flow) at suction

39 39 MENU Main Menu Basic Hydrostatic (closed circuit) System Overview Functionality of components Hydraulic Fluids FiltrationReservoir Heat Exchanger

40 40 MENU 6. Heat Exchanger Function and Type Removal of hydraulic-system heat Prevents overheating of oil Ideal oil-temperature should be 60 to 80°C Construction type in mobile hydraulic Oil-air-heat exchanger Oil-air heat exchanger

41 41 MENU 6. Heat Exchanger Design Criteria vehicle engine cooler fan SD FD system

42 42 MENU 6. Heat Exchanger Sauer-Danfoss Fan Drive example: closed circuit

43 43 MENU The End MENU

44 44 MENU Many Thanks for YOUR Attention! When Chuck Norris says 420 bar" he is not quoting the pressure rating of the H1B motor, he is telling you how much pressure his foot will apply to your face. The three things that make hydraulics work: 1. Flow 2. Pressure 3. Chuck Norris

45 45 MENU Overview Literature Sources MENU - Source 1 -Ölhydraulik – Handbuch für die hydrostatisch Leistungsübertragung in der Fluidtechnik; Findeisen, D.; Springer


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